Dimension 8400, no post, no video

I've got a winner on my hands here, I have a Dimension 8400 from Dell, and all was well with the refurbish until tonight.

Dell tried to tell me it was the PSU, but I have my doubts.

I get no POST, no video, and the fan screams like a banshee.

No integrated graphics, and I have no spare PCI-E card.

It locked up when I was in the BIOS setup, and had to be shut down, and then the current symptoms began.

Need to test PSU, and am worried it is the MOBO.

Anyone seen this before?

By the way, diagnostic lights indicate A, C, & D are green, and B is orange.

 

Which fan as that's an obvious starting point.

 

System fan Augie.

SCREAMIN' like a banshee.

Looks like the PSU is solid, and I'm thinkin' mobo.

Just lookin for some reassurance before I throw out sixty bucks on one.

 

Took a hard look at the caps, looks like the heat issue with the Prescott core probably did one in.

I have always loved Dell for their cooling solutions, but I think they dropped the ball on this model.

 

Maybe this will help, although I see nothing there with the light pattern that you see. Can you identify any of the beep patterns?